package com.itheima.config;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import java.util.List;

@Slf4j
@Configuration
public class WepMvcCongif extends WebMvcConfigurationSupport {
    /**
     * 释放静态资源映射器
     * @param registry
     */
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
       log.info("释放静态资源");
        registry.addResourceHandler("/backend/**").addResourceLocations("classpath:/backend/");
        registry.addResourceHandler("/front/**").addResourceLocations("classpath:/front/");

        registry.addResourceHandler("/doc.html").addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
    }

    /**
     *
     * 扩展springmvc 里面的消息转化器
     * 当数据库里面的数值很大的时候,js页面接收不到这么精确的值js只能精确到16位数
     */
    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        System.out.println(converters);
        //创建消息转换器对象
        MappingJackson2HttpMessageConverter  messageConverter =new MappingJackson2HttpMessageConverter();
        //设置对象转换器，底层使用Jackson将Java对象转为json
        messageConverter.setObjectMapper(new JacksonObjectMapper());
        ////将上面的消息转换器对象追加到mvc框架的转换器集合中,注意需要把这个对象方法放到集合的最前面
        converters.add(0,messageConverter);

    }
}
